One process of transient rewetting has been experimentally characterized by the advance of a boiling front whose length is small with respect to the rod dimensions and whose rate of advance is nearly constant in time. With suitable coordinate transformations, the rewetting rate has been satisfactorily described by one (or two) dimensional heat conduction in the rod, coupled to the heat removal in the falling film by an average heat transfer coefficient and an assumed maximum temperature at the boiling front. To resolve present uncertainty in the choice of the coupling heat transfer coefficient and the maximum wetting front temperature, experiments were carried out in which detailed temperature profiles were obtained throughout all regions of a stationary boiling front on a vertical rod. Analysis of these experimental data show that for unconfined sputtering on a vertical rod, the maximum temperature at the boiling front is that associated with the point of DNB. This suggests that the boiling front may be modelled by assuming a nucleate boiling process. Based on this concept, one- and two-dimensional heat conduction effects are compared and a simplified one-dimensional model is illustrated and verified.
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- General Materials Science
- Nuclear Energy and Engineering
- Safety, Risk, Reliability and Quality
- Waste Management and Disposal
- Mechanical Engineering